The invention relates generally to a thrust reverser for gas turbine fan-jet propulsion engines utilized in modern aircraft and more particularly to deploying mechanism therefor.
Various different types of fan gas reversers presently exist, most of which are considered to be useful for their intended purpose. Some of the prior art reversers utilize cowl section translation with simultaneous deployment of reverse or blocker donors, as well as providing an opening in the cowl surrounding a turbofan engine with a translatable cascade ring being positioned thereon to provide an exit and direct the gases forwardly through.
Actuation mechanism generally consist of link and liner actuator combinations for both cowl section translation and reverser or blocker door deployment.
A novel two-part reverser or blocker door is taught by U.S. Pat. Nos. 3,964,257 and 4,073,440, wherein the abutting ends of the reverser or blocker doors form curved single rack gears with interlocking and meshing teeth so that both reverser or blocker doors operate simultaneously between their stowed and deployed positions.
A clam shell type thrust reversing mechanism having curved single rack gear abutting ends on each clam shell reverser or blocker door for simultaneous movement between their stowed and deployed positions is taught in U.S. Pat. No. 3,759,467.
U.S. Pat. No. 3,612,399 teaches the simultaneous deployment of reverser or blocker doors while translating the door aft by use of a single screwjack with separate threaded portions of different thread pitch. The mechanism provides for rearward translation of the reverser or blocker doors at a faster rate than the door deployment to a full blocking position.
British Pat. No. 778,008 teaches the use of separate actuators, one to first translate the reverser or blocker doors aft and one associated with each reverser or blocker door for their simultaneous deployment after translation.
U.S. Pat. No. 2,972,860 teaches two reverser or blocker doors of the clam shell variety pivotally connected to each other in their down stream end portions for rotation in opposite directions about an axis normal to the axis of the engine and are jointly controlled by a first actuator for translating the doors aft and a second actuator for rotating the doors into the path of the engine gas stream.
As aforementioned, most of the existing thrust reversing mechanisms have various merits and in most instances have been used with some degree of success. The principal objections have included requirements for excessive operating mechanisms to insure uniform and sometimes simultaneous translation and deployment of reverser or blocker doors that result in excess-weight, which is critical in modern aircraft, higher economic costs and over-all complexity with the resulting high maintenance both in aircraft down time and economic cost, and very little, if any, consideration in design was directed toward maintaining excess area size balance during the translation and deployment of the reverser or blocker doors to prevent possible loading or stalling of the engine through back pressure.